It's particularly bad for them but that doesn't mean it's perfectly safe otherwise. I wouldn't use it at all with cats or especially dogs, since they explore their world with their noses. A lot of the claims that it's safe for pets say something about if it's food grade, it's safe for pets to ingest the small amounts needed for pest control and then ignore how dogs get right up to things with their nose when they say "but don't inhale it!"

https://www.earthworkshealth.com/post/myths-and-misconceptions-about-diatomaceous-earth